He had noticed that a new DCS391 performed better than an older one, and that it had higher speed specification.

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Bill wrote:

I went to Lowes and picked up a new DCS391 and found it to be a much better performing tool than my older unit at home. It wasn’t until I returned home and compared both tools did I discover that my older unit has a Type-1, 3700/min printed on the label and the new one has Type-3, 5150/min.

Both tools are otherwise very close in outward appearance and features, including the 3D magnesium base. Does Dewalt do this with other tools? I can’t find mention of the difference between the two on Dewalt’s website. Was there ever a Type-2?

We asked Dewalt about this, and they said:

In June of 2015 we made an improvement to the motor to increase the tool’s performance.

This is not the first time we’ve seen improvements made to current Dewalt power tools. Their DW745 was updated a few years ago with a greater ripping capacity, and I am aware of revisions to Dewalt’s miter saws.

*Thumbs up* Dewalt. It’s good to see that improvements are sometimes made in a product’s lifetime, and that they’re not just held back for later-on models.

19 Comments

Dewalt’s Marketing department slept through that one. They should have provided Stuart a new one immediately.

Really.

But Kudos to Dewalt Engineering and Production for constant improvement. I love my Bosch cordless saw, I have no need to upgrade, but things like this is why Dewalt rules so much of the cordless market (and Milwaukee for that matter).

I was told at one point the motor RPM was increased due to the advent of higher capacity batteries that had been released (ie. 5.0ah). With the higher capacity batteries the motor could spin faster for longer giving more power for cuts.

While this has proven to be slightly true, I bet they did tweak the motor to perform better with the improved batteries that were hitting the market in 2015.

Since I do this for a living, I will attempt to explain what went on at Dewalt when they decided not to announce the change. Imagine Dilbert and the pointy haired boss talking.
Person 1: “This is so much better, we should tell everyone and release it as a new model.”
Person 2: “Do you have any idea how many units we have of the slower motor in the channel? Do you know how many people will return ones they’ve just bought or wont buy one because its slower? How much are we going to have to mark down the slower ones to keep the big box stores happy?”
Person 1: “I’ve got a great idea, lets not announce a specification change… we will make a silent running change and just flush the old units through the channel. At some point we will announce the change.”
(time passes – Person 1 and Person 2 both forget about the spec change because they are deep in the throws of arguing that the shade of Yellow on the new boxes doesn’t quite match the corporate standard)

from a marketing standpoint; almost guarantee it’s what John Blair said…although, I doubt it has anything to do with consumers, more to do with the retailers that hold inventory. They’re the ones that will attempt to exchange them if a public announcement is made, as they’re the ones that have to explain why the two models cost the same otherwise.

or discount them, but the retailers weren’t given the wholesale discount to begin with…and it just gets messy.

This is common in almost any type of electronic. Updates are made, and legally there has to be some sku # changes to reflect that, but manfucturers lobbied enough to make it that there doesn’t have to be enough transparency that ‘everyone’ knows about it before purchase. Not complaining, just saying it’s very much part of most electronic businesses. The good news is that in most cases a simple return and exchange isn’t all that difficult if still within a certain window. Otherwise, it’s just a matter of accepting that things you buy get replaced with better versions all the time haha.

That timing is interesting, I ordered the bare tool model, DCS391B from Lowes in Canada on 6/6/15 and it says Type 3 on the label. It is possible of course that these items turn over very quickly, but I would image the enhancement must have been made some time before June 2015.

I knew about this for a long time, my friend had the original when they first came out, and bought mine last year and I noticed mine had more power, they looked on the tool mine said 5125 rpm his said 3700 rpm my Dewalt is as powerful as the brushless Milwaukee, it might not get as many cuts but power wise they cut about the same speed, when it comes to saws brushless doesn’t make that big of a difference not like drills and impact driver where you get a 40 to 50 % increase in runtime with a saw you get about 10% increase

Huh… I’ll check mine, got it last summer, I hadn’t noticed if it was “improved” because I’ve never used another one. While obviously not as strong as a 15 amp corded saw it’s still my primary use saw, my only complaint is runtime.

I’m the guy, Bill, who posted the initial comment Stuart refers to. I agree with most of the comments above and I also think it was most likely a marketing decision not to tout this tool improvement. But, at an almost 40% increase in RPM from the Type-1 to the Type-3 I can attest to the much improved cutting performance. I was never very impressed with the rather anemic cutting speed of my first Type-1 version of this tool but now that I have the Type-3 I’m sure I will use it more often.
More importantly, this experience has influenced my next buying decision on a cordless 7-1/4″ circular saw. I am leaning towards the Dewalt Flexvolt saw because it spins at 5800 rpm, about 16% higher than the Milwaukee M18 Fuel’s 5000 rpm. I’m assuming the Flexvolt will also spin higher than the yet to be released Dewalt 20v max 7-1/4″ circular saw.

If all 3 were available now, I’d lean towards the new 20V Max, with the 60V Max FlexVolt a very close second pick. This 20V Max model is great, and a better value for more casual users who don’t need the 7-1/4″ blade size.

I own both the 60v and 20v cordless saws. By far the 60 is the way to go it runs all day on one battery cutting siding. And you will have to switch batteries at lunchtime if you are just framing up a small building or pole shed.

Very interesting that they decided to down grade the rpm, if only slightly, from the Type-2 and release it as a Type-3. While it’s impossible to know for sure it sounds more like a marketing decision vs. an engineering call.

It’s almost certainly not a marketing decision as it was never “marketed” as an upgrade or feature.

The RPM listed on tools is the “no-load speed” which has literally no relationship with the overall power of the saw. The size, efficiency and wattage of the motor would tell you more than knowing the no-load RPM.

For example a Dyson vacuum has a motor that spins over 100,000 RPM and meanwhile a large diesel engine in an ocean liner only spins at 1,800 RPM but there is no question which has more power.